As we age, the ways that we sense the world around us start to change with our bodies. Our senses of taste, smell, hearing, and sight become less sharp. Now, new research has shown that even our perception of color dims over time.
Researchers from University College London (UCL) recently compared how the pupils of younger and older people reacted to colors in the environment.
The team recruited a small sample of 17 young adults (average age was 27.7 years) and 20 healthy older adults (with an average age of 64.4). The participants were placed in a blackout room where they had the diameter of their pupils measured by a highly sensitive eye tracking camera while they were shown 26 different colors, each for five seconds.
The colors shown included various shades – including dark, muted, saturated, and light – of magenta, blue, green, yellow, and red. Participants were also shown two shades of orange and four greyscale colors.
When we see color, our pupils constrict in response to any changes in its lightness or chroma (colorfulness). Usually this is difficult to observe in an individual, but the tracking camera used by the team, known as a pupillometer, was capable of recording changes in pupil diameter at 1,000 times per second.
During their analysis, the team found that the pupil diameter of healthy older people constricted less in response to color chroma compared with their younger counterparts. This was particularly apparent for green and magenta hues. However, both sets of participants had similar responses to the “lightness” of a color shade.
“Our pupillometry data suggest that we become physiologically less sensitive to the colorfulness of our environment as we age,” the authors write. “These findings complement earlier behavioral research which showed that older adults perceive surface colors as less chromatic (colorful) than young adults.”
“We therefore propose that colors fade with age, and that we become specifically less sensitive to the relative Green or Magenta saturation level of colors. Our findings show no reduced pupil responses to relative Blue saturation level of colors.”
According to a statement from the lead author, Dr Janneke van Leeuwen, “This work brings into question the long-held belief among scientists that color perception remains relatively constant across the lifespan, and suggests instead that colors slowly fade as we age.”
Dr van Leeuwen added, “Our findings might also help explain why our color preferences may alter as we age – and why at least some older people may prefer to dress in bold colors.”
The team believe that, as we get older, there is a decline in our body’s sensitivity to color’s saturation levels within the primary visual cortex, the part of the brain that receives, integrates and processes visual information communicated to it from the retinas.
In previous work, a rare form of dementia, called posterior cortical atrophy (PCA), was found to share this feature. In PCA, there is are noticeable difficulties and abnormalities in color perception which could come from a signature decline in the brain’s sensitivity to certain color tones – again, green and magenta – in the primary visual cortex and its associated networks.
“Our findings could have wide implications for how we adapt fashion, décor and other colour ‘spaces’ for older people, and potentially even for our understanding of diseases of the ageing brain, such as dementia,” Professor Jason Warren added.
“People with dementia can show changes in colour preferences and other symptoms relating to the visual brain – to interpret these correctly, we first need to gauge the effects of healthy ageing on colour perception. Further research is therefore needed to delineate the functional neuroanatomy of our findings, as higher cortical areas might also be involved.”
The paper is published in Scientific Reports.